The present invention relates to a combined alternator compressor for providing both the electrical energy generating function and the air conditioning refrigerant pumping function in an automotive vehicle.
Automotive vehicles have customarily included an internal combustion engine as a prime mover which, in addition to supplying energy to propel the vehicle, drives a number of ancillary devices. The engine ordinarily drives an electrical generator or alternator and several pumps including an air conditioner pump or compressor. These devices are driven by way of belts, pulleys and the like.
Typically the alternator and refrigerant compressor will each be driven from the engine crankshaft by way of V-belts and pulleys. The alternator typically revolves at high speed to generate a relatively high frequency alternating voltage. The compressor is typically driven by means of an electromagnetic clutch. Much of the time the electromagnetic clutch is not actuated and the compressor pulley is freewheeling and contributes nothing to the loading of the engine except frictional losses. When the system calls for the compressor to pump refrigerant, the clutch is actuated and causes the compressor pulley to drive the compressor.
One of the problems with the above-described automotive systems is that the utilization of a separate alternator and a separate compressor entails relatively large space and weight requirements. This is undesirable, particularly in today's energy-conscious society where space and weight are at a premium in the automotive environment because of the relatively high cost of energy and the resultant trend towards smaller automobiles. Furthermore, the use of separate alternators and compressors is relatively expensive as it requires the use of a large number of parts.
In some prior art systems the alternator and compressor have been combined into one unit. One example of such a combined alternator compressor unit is disclosed in U.S. Pat. No. 4,095,922, which is assigned to the same assignee as the present application. While the disclosed structure operates satisfactorily, a disadvantage of the structure is that it is relatively complex. Additionally, due to the high rotational velocities at which alternator-compressors operate alignment is critical and has not been easy to achieve with the prior art structures.
Furthermore it is important, due to the stringent space and weight requirements of the automotive environment, that combined compressor alternator units be made as compact and light-weight as possible. Lastly, it is extremely important that magnetic losses in the compressor clutch structure be kept to a minimum to increase efficiency whereby a small clutch field coil can be used for generating the magnetic field for the clutch structure.
It is therefore desired to provide a unitary alternator-compressor which is small, very compact, light-weight and simple in construction.
It is also very desirable that unitary alternator-compressors have a small axial dimension because of the small engine compartments available in automobiles.
Furthermore, it is desired that the parts of an alternator-compressor each perform multiple functions whereby the number of parts required in the prior art structures can be reduced and the structure simplified.
It is still further desired to provide an alternator-compressor wherein alignment of the clutch is relatively simple and easy to achieve and wherein the magnetic losses in the clutch structure of the unit are kept to a minimum.